Transmission
     The virus, as stated earlier, is passed to people, horses, and other animals, specifically birds, through the bite of an infected mosquito. The most common transmission has been to birds, particularly crows and jays, and also from birds to mosquitoes. In other words, transmission is a vicious cycle. Mosquitoes become infected through feeding on the blood of an infected bird, and from here, mosquitoes pass it to uninfected birds. From here, the cycle begins again. Although many birds have been infected with the virus, only a small percent actually perish from it. No evidence has been found that people can contract West Nile Virus from handling both living or dead birds.

Symptoms
      As stated above, most people who come down with West Nile Fever will only exhibit mild symptoms, including fever, headache, body aches, and occasionally a rash on the trunk of the body and swollen lymph glands. These symptoms usually only last a few days. Symptoms of severe infection (West Nile Encephalitis or meningitis) include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis. This severe form of the illness has a 3 to 14 day incubation period. Symptoms may last several weeks, but neurological damage may be permanent.

Testing & Treatment
      Symptoms of West Nile Virus can often be misinterpreted because they are flu-like in nature, unless they start to point to West Nile Encephalitis. If you are concerned that you may have West Nile, please contact your Doctor. If symptoms progress, seek medical attention immediately. Your physician can perform a blood test to check for the virus.

      Treatment depends on the severity of the manifestation of the virus. Mild cases will be allowed to run their course usually with no major interventions required. In more severe cases, intensive supportive therapy is indicated, often involving hospitalization, intravenous fluids, airway management, respiratory support (ventilator), prevention of secondary infections (pneumonia, urinary tract, etc.), and good nursing care.

Horses and West Nile
     40% of all cases of West Nile in horses result in death. Most horses tend to recover, however. There is no evidence that shows that the virus can be passed back to mosquitoes through biting an infected horse. Also the disease cannot be passed from horse to horse, horse to bird, or horse to human. “In horses that do become clinically ill, the virus infects the central nervous system and causes symptoms of encephalitis. Clinical signs of encephalitis in horses include loss of appetite and depression, in addition to any combination of the following signs: fever, weakness or paralysis of hind limbs, muscle fasciculations or muzzle twitching, impaired vision, ataxia (uncoordination), head pressing, aimless wandering, convulsions, inability to swallow, circling, hyper-excitability, or coma.”(Ohio State University Extension, West Nile Virus Workgroup.) There is a new vaccine for horses, but its effectiveness is yet unknown. It is imperative that horses are vaccinated twice, 3 to 6 weeks apart, initially with this vaccine. At least 1 yearly booster is recommended after the initial series. Horses that are stressed such as show and race horses should have 2 boosters annually in April and late July. Horses vaccinated against Eastern, Western, and Venezuelan equine encephalitis are not protected against West Nile Virus.(Ohio State University Extension, West Nile Virus Workgroup.). Currently, there is no treatment for West Nile Virus in horses beyond supportive veterinary care.

Preventative Measures

Mosquito Repellant
      One of the best defenses against West Nile Virus is using mosquito repellants containing DEET (N,N-diethyl-m-toluamide) when spending any time outdoors, especially in the morning and evening hours. DEET has been proven to be safe both in children and adults. There have been only a scarce amount of any type of adverse reactions, and those that have occurred were an allergic type of reaction. DEET has been very successful in camouflaging people from mosquitoes. DEET comes in various concentrations in mosquito repellants. For example, a product containing 20% DEET on the average provide almost 4 hours of protection, although products with a concentration of 50% or more have not been proven to have a longer length of protection than those much over 20%. “The American Academy of Pediatrics has recommended that a cautious approach is to use products with a low concentration of DEET, 10% or less, on children aged 2 - 12. Most guidelines cite that it is acceptable to use repellents containing DEET on children over 2 years of age. Other experts suggest that it is acceptable to apply repellent with low concentrations of DEET to infants over 2 months old” (CDC). The strength used should coordinate with length of time spent outdoors. If you should sweat or get wet, repellant may need to be reapplied more frequently. If you are not being bitten, reapplication is not necessary.

Mosquito Repellant Tips
1. Do not apply repellant to cuts, wounds, or areas of irritated skin.
2. Just enough to cover the surface of the skin is all that is necessary. It is not necessary to apply under heavy clothing. If you are wearing thin clothing, they may need to be sprayed to prevent mosquitoes from biting through them.
3. When returning indoors, clean repellant off with soap and water.
4. Do not use spray repellants indoors.
5. Avoid contact with eyes and mouth. Rub repellant onto face using hands.
6. Rub rather than spray repellant when applying to children.
7. Use Sparingly around children’s ears.
8. Do not apply repellant to children’s hands, as they may put them in their mouth and eyes.
9. Do not allow children to apply repellant to themselves.

Other Preventative Measures
1. Wear long sleeved shirts and long pants when possible when spending time outdoors.
2. Keep mosquito netting over infant carriers when outdoors.
3. Stay inside during the prime mosquito hours (morning and evening).
4. Make sure screens are in good repair. If you do not have screens, they may be worth investing in.
5. Don’t leave old, stagnant water sitting around. Empty and refill empty water from flower pots, pet food and water dishes, birdbaths, swimming pool covers, buckets, barrels, and cans about twice a week.
6. Keep gutters clean and in proper working order.
7. Discard any old tires that may hold water.
8. Keep outdoor light usage to a minimum. Light attracts mosquitoes.
9. Keep ornamental pools aerated or stocked with fish. Water gardens can become major mosquito producers if they are allowed to stagnate. Clean and chlorinate swimming pools, especially when not in use. A swimming pool left untended for a month or more can produce enough mosquitoes to infest an entire neighborhood.

Prevention for Horses
1. Keep Horses indoors during the peak morning and evening mosquito periods.
2. Keep light usage to a minimum in the morning and evening. Lights attract mosquitoes.
3. Place incandescent bulbs around the perimeter of the stable to attract mosquitoes away from the horses. Black lights don't attract mosquitoes well.
4. Do not keep any types of birds in or around the stable, including chickens.
5. Check property periodically for dead birds and report them to the local health department. Use gloves to handle dead birds or use an implement, such as a shovel.
5. Eliminate areas of standing water on your property. Shallow standing water, used tires, manure storage pits, and drainage areas with stagnant water are ideal mosquito breeding places.
6. Topical preparations containing mosquito repellents are available for horses. Read the product label before using and follow all instructions.
7. Use fans on the horses while in the stable to help deter mosquitoes.
8. Fog stable premises with a pesticide in the evening to reduce mosquitoes. Read directions carefully before using. For help in assessing mosquito exposure risks on your property and for suggested control practices, please contact your county Extension office, county Department of Environmental Protection, local Department of Health, local veterinarian, or mosquito and pest control company.